Answer:

13) 1, 2, 4, 6, 8

14) 1, 2, 5, 10

15) 1, 2, 4, 8

16) 1, 2, 3, 4, 6

HOPE IT HELPS :)

[See the attached image for the answers]

Step 1: List all the factors of a number

Step 2: Comapare the factors and

Step 3: If a factor appears in both lists then that's the common factor/s